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Re: [patch] Fix PR middle-end/56474
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 15 Apr 2013 12:04:14 +0200
- Subject: Re: [patch] Fix PR middle-end/56474
- References: <1630485 dot 0zg5rbKfGZ at polaris> <CAFiYyc2H_=fCKGZ3yDG+RoTQWXkCDJ9=HY_Kttr_LKPtdjDTpw at mail dot gmail dot com>
> I think I already rejected this and asked you to fix the users (like
> layout_type is a user).
Yes, but that would be a pain, there are too many users in the Ada front-end.
> Clearly 0 - 1 in unsigned arithmetic overflows. Not indicating this may
> cause bugs elsewhere as easily as it fixes code not dealing with this fact.
!?? There is no overflow in unsigned arithmetics. Instead size_binop forces
overflows artificially and I don't see the problem in deciding that 0 - 1 is a
special case, like [0, -1] is a special case for layout_type. And note that
this was the historical behavior, before the latest sizetype changes.